The Arabic-decimal system of numbering has served us well during the 500 years since it replaced the Roman numeral system. However, the ever extending use of computers and other digital systems which employ the binary numbering system indicates that the Arabic-decimal system may soon be retired in favor of a system which is compatible with the binary system. The base-16 system is such a system--with its grouping of binary bits into groups of four.
To further accommodate communication with binary digital systems a "Computer Compatible Digit" becomes useful. Such a digit consists of four elements, each element corresponding to a bit of the corresponding base-16 digit. The digit may be visible as discussed in copending U.S. Pat. Application Ser. No. 593,434--or audible as disclosed in the present Application.
A prime use for audible digits is in clocks. It is convenient to have a clock announce the time on the hour and at other appropriate intervals. Audible digits are also of utility in instrumentation where an operator needs to know a digital value but cannot take his eyes from a process or object being observed. Audible digits become useful for passing numerical information to aircraft pilots and to automobile drivers. Such audible digits may be spoken words of the English or other language. They may be bells, whistles, or tones. The only requirement is that the sound or sounds generated be recognized by the human auditory system as representing a particular digit. Since electronic digital equipment generally represents digits by four signal bits each of which may be high or low, it becomes convenient to form audible digits from four audible bits, each of which may be either high or low. The present invention provides implementation for such a system.